Construction hero is free (sage of storm)Research hero is The trickster ( 2-6 elite )Farm as much trickster medals as you can and increase he grade.

Player level 26 onwards

Reset hero talent ( 90k guild coins )

Max out construction speed 1 Max out research speed 1.Max out research speed 2.Once research speed is maxed, start researching t2 unit ( should be a lotttttt faster, now that you have ++research speed )Max out construction speed 2.